Device for supplying liquid fuel to burners



United States Patent Inventors Reiner Frledl Starnberg; Robert von Llnde, Grafelfmg, Germany Appl. No. 664,144 Filed Aug. 29, 1967 Patented Nov. 3, 1970 Assignee Webasto-Werk G.m.b.11.

Munich, Germany Priority Nov. 10, 1966 Austria A 10,388/66 DEVICE FOR SUPPLYING LIQUID FUEL TO BURNERS 4 Claims, 1 Drawing Fig.

vs. 01. 137/100, 261/69,l37/85,137/487,137/489,137/500, 137/604 1m. 01. G05d 16/06,

[50] Field ol'Search 137/85, 87, 98, 99,101.11, 487, 489, 494, 497, 500, 505, 505.37,100, 604,158

[56] References Cited UNITED STATES PATENTS 1,744,872 l/1930 Earl 137/9 2,483,426 10 /1949 M0ore..... 137/98 2,962,094 11/1960 Wallace.... 431/90 3,267,987 8/1966 Fried] 137/197 Primary ExaminerWilliam F. ODea Assistant Examiner-William H. Wright Attorney- Otto John Munz ABSTRACT: A device for supplying liquid fuel to a burner having a high pressure air supply with a venturi section in the air supply line, and a venturi-pressure controlled fuel dosing device which includes a fuel proportioning nozzle and a membrane-operated flutter valve. One control chamber of fuel dosing device is a part of the fuel delivery conduit, and the fuel enters the air delivery conduit at the constriction portion of the venturi section.

Patented Nov. 3, 1970 3,537,468

lnvehtors: Reiner Fried! Robert van Linde Atto ney DEVICE FOR SUPPLWNG MQUHD FUEL T EUlithllE itS The invention relates to a device for supplying liquid fuel to the burner of a heating appliance used in vehicles, such device may be equipped with a high-pressure blower for irnpelling the air for combustion, into the delivery conduit of which blower a fuel pipe opens at a point where a low-pressure zone is generated (e.g., by means of a venturi tube), and the fuel pipe may be fitted with a proportioning nozzle to effect fuel dosage.

DESCRlPTlON OF THE PRIOR ART Devices of this kind, operating with low-pressure blowers, but not incorporating a p'roportioning nozzle, have been described, but only in conjunction with burners of larger capacities, and even so their applicability is restricted to certain specific cases.

However, a fuel supply means similar to the above has been employed with good results for burners having smaller capacities, in which the venturi tube together with the inlet orifice of the fuel pipe is arranged in the suction conduit of the high pressure blower. also using In conjunction therewith u membrnne'cquippcd dosing device. This embodiment suffers from the disadvantage that the fuel must be conveyed at all times through the high-pressure blower which, on one hand, imposes restrictions with regard to the type of blower employed and, on the other hand, increases the breakdown susceptibility of the system, in that a failure of fuel admission results in the dry operation of the blower, normally lubricated by the fuel, so that disturbances occur after a relatively short time unless prevented by additional safety measures.

SUMMARY OF THE INVENTION The object of the present invention is to provide an apparatus which, when operated with high-pressure blowers, allows the use of different types of blowers, and avoids breakdowns in case of interruptions of the fuel supply, so that no extra safety precautions are required in this respect.

To achieve the above-defined object, it is proposed accord ing to the invention to employ in a device of the kind first mentioned a dosing device divided by a membrane into an admission and a delivery chamber, the admission chamber being situated upstreams of the nozzle when viewed in the direction of fuel flow, and the membrane controlling a valve located between the admission chamber and a fuel tank, and wherein the delivery chamber is connected with the delivery conduit of the high-pressure blower. By this last-mentioned measure the membrane control does not operate with excessively large pressure differentials, which in turn makes possible a faultless proportioning of the fuel supply and also offers further advantages in view of the consequently smaller variations of the fuel/air ratio in the case of variations in the delivery rate of the high-pressure blower.

In a preferred form of the device according to the invention, there is employed a pump connected between the membranecontrolled valve of the dosing device and the fuel-storage vessel, whose delivery automatically ceases when a predetermined pressure is reached in the pump delivery pipe, for example an electromagnetically operated diaphragm pump as described in the U.S. Pat. No. 3,267,987. Compared with a construction involving a relief valve and a return conduit, this feature is advantageousby virtue of the resulting savings in driving energy and is also preferable for constructional reasons. In any case, the important condition is to have the fuel flowing under pressure to the admission chamber of the dosing device, so as to enable the inflowing fuel to influence the pressure conditions in the delivery chamber.

According to a further preferred feature of the device in accordance with the invention, the connection of the delivery chamber of the dosing device with the delivery pipe of the high-pressure blower is provided between the latter and the inlet orifice ofthe fuel pipe.

BRlEF DESCRlPTlON OF THE DRAWlNGS HO. 1 is an elevated front view, partially in cutaway section, ofa fuel supply device embodying the invention.

DESCRIPTION OF THE PREFERRED EMBODih/IENT The following description, referring to the accompanying drawing, discloses a preferred embodiment of the device according to the invention, and illustrates further features of the invention.

To a burner 2 comprising an ignition device 1 fuel is fed from a fuel storage container 3 through an electromagnetically operated and spring-controlled diaphragm pump i, a dosing device 5 and a delivery pipe 6. The dosing device 5 in question comprises a'venturi tube 7, a proportioning nozzle 8, a membrane 9 and a controlled fuel valve ill. The control membrane 9 divides the cavity of the dosing device 55 into an admission chamber ill and a delivery chamber 2. The control ofvalve ll) is effected by a push rod 14, having a groove 13.

The air for combustion is supplied to the humor 2 by it high" pressure blower lo driven by on electric motor l5, said blower 16 being connected with the air inlet l? olthc burner I2 by Way of the delivery conduit 6. the venturi tube 7 and that portion of the delivery conduit, referenced 18, which is situated upstream of the venturi tube.

During delivery by the high-pressure blower it), the venturi tube 7 reduces the pressure in the admission chamber ill of the dosing device 5, which results in a downward movement of the membrane 9 and thus the opening of valve l0. Since, owing to the presence of the pressure equalizing conduit 19 extending from the delivery chamber 12 and the delivery conduit 18, no very large pressure differences occur between the admission chamber and the delivery chamber, the fuel entering under pressure through valve id into the admission chamber ill effects a certain equalization of pressure and in consequence there is a return movement of the membrane 9, which again closes or almost closes the valve it). This intensities the low pressure created by the venturi tube 7 in the admission chamber ll, which again leads to a downward movement of membrane 9, and the consequent increased opening of the valve 10. In operation, while the membrane executes a hardly visible fluttering motion, a prearranged open position of valve 10 is established which, for a suitable coordination of proportioning nozzle 8, venturi section 7 and the output of the high-pressure blower 16, corresponds to the desiredrate of fuel admission.

The pressure equalizing conduit 19 may alternatively be connected with the portion 6 of the delivery conduit, located downstream of the venturi tube 7; in general, the invention is in no way restricted to the details herein described and illustrated, but may be modified in different ways in application of the principles described.

We claim:

l. A device for supplying liquid fuel to burners, comprising:

a burner inlet;

an air supply means to supply combustion air at a high pressure to said burner inlet;

an air delivery conduit connected between said air supply means and said burner inlet;

a fuel supply means to supply liquid fuel to said burner inlet;

a fuel delivery conduit connected between said fuel supply means and said burner inlet;

a fuel dosing means to control the flow of fuel in said fuel delivery conduit; said fuel dosing means including a control valve means, an admission chamber, a delivery chamber, a flexible mernbrane means separating said admission chamber from said delivery chamber, and by its movement operating said control valve means, and a fuel proportioning nozzle;

said control valve means, admission chamber, and proportioning nozzle being integral parts of said fuel supply conduit, so that the'liquid fuel passes thcrethrough in succession;

said air delivery conduit including pressure control means to control the pressure within said admission chamber thereby controlling the degree of opening of said control valve means; and

said fuel supply means including fuel pump means arranged upstream of said fuel dosing means and adapted to supply liquid fuel to said fuel delivery conduit at a substantially constant pressure and at a variable flow as determined by said control valve means.

2 A device for supplying liquid fuel to burners, comprising:

a burner inlet;

an air supply means to supply combustion air at a high pres sure to said burner inlet;

an air delivery conduit connected between said air supply means and said burner inlet;

a fuel supply means to supply liquid fuel to said burner inlet;

a fuel delivery conduit connected between said fuel supply means and said burner inlet;

a fuel dosing means to control the flow of fuel in said fuel delivery conduit;

said fuel dosing means including a control valve means, an

admission chamber, a delivery chamber, a flexible membrane means separating said admission chamber from said delivery chamber, and by its movement operating said control valve means, and a fuel proportioning nozzle;

said control valve means, admission chamber, and proportioning nozzle being integral parts of said fuel supply conduit, so that the liquid fuel passes therethrough a succesmen;

said air delivery conduit including pressure control means to control the pressure within said admission chamber, thereby controlling the degree of opening of said control valve means; and

said pressure control means includes a vcnturi-section hav ing a constricted portion within said air delivery conduit and a communicating conduit between said constricted portion and said admission chamber of said fuel dosing means, so as to vary the pressure within said admission chamber in accordance with the speed of air flow in said delivery conduit.

3. A device as claimed in claim 2, wherein said fuel delivery conduit and said air delivery conduit are joined at a point upstream of said burner inlet.

4. A device as claimed in claim 2, wherein said fuel delivery conduit and said air delivery conduit are joined at said constricted portion of said air delivery conduit, and wherein said communicating conduit is an integral part of said fuel delivery conduit. 

